Series of detective/comedy novels by Anthony Horowitz, featuring would-be private eye Tim Diamond (real name Herbert Simple) and his kid brother Nick. Despite believing himself to be a genuinely brilliant detective, Tim is utterly hopeless, and all of the cases are solved by Nick him despite never getting any credit, with the occasional help or hindrance of supporting characters Chief Inspector Snape of Scotland Yard and his sidekick Boyle.
The novellas have been collected in Three of Diamonds (later retitled Four of Diamonds with the release of The Greek Who Stole Christmas). The first novel was adapted for the big screen in 1989 under the name Just Ask For Diamond, and South by South East was made into a TV series in 1991 using the same cast.
Provides Examples Of:
Adults Are Useless: Nick manages to outwit each and every adult he encounters, be it the police, his older brother, or a master criminal.
Black Dude Dies First: Inverted - Mark Tyler, the only black character in I Know What You Did Last Wednesday, is the final character to die (albeit by a matter of seconds).
Blatant Lies: There are several examples, mostly from Nick trying to cover up Tim's incompetence, but the best example has to be in Public Enemy Number Two, when Tim announces to a group of criminals he and Nick are meant to infiltrate that he is a private detective; as the mood rapidly turns frosty, Nick makes up a spur-of-the-moment tale that he is a private investigator of water, "having to check there is enough H". Incredibly, this works.
Clueless Detective: Tim, often taken to extremes; the one time he manages to solve a case, not only is it completely by accident, he's on the run from the law at the time, and he promptly destroys the priceless Ming vase he was meant to be finding by accident. The logo of the series features the words 'Diamond Brothers Detective Agency', with a scratch over the first 't' in 'Detective' making it seem like it actually says 'Defective'.
Comic Book Time: The original books came out in the late 80s and early 90s. The more recent novellas, released over a decade later, have Tim and Nick at the same age but feature modern-day concepts such as the London Eye.
Courtroom Antic: Subverted by Public Enemy Number Two: when Tim is called as a witness to Nick's trial, he does proceed to make a complete mockery of the legal system by saying increasingly stupid things, but he is completely unaware he's doing so and it more or less secures Nick's conviction.
Hypercompetent Sidekick: Nick. Whilst Tim faints at the slight of blood and is constantly caught at the scenes of murders holding incriminating evidence (typically the murder weapon), he solves every single case.
Parental Abandonment: Inverted in that Nick chose to abandon his parents when they emigrated to Australia.
Perpetual Poverty: Sort-of. The brothers do actually make the odd windfall - they just always lose it not long afterwards. Nick even predicts this in the first book, noting that, having finally gotten enough money for a holiday, they'll probably have to spend it all on treatment after Tim inevitably breaks his leg or something.
Piano Drop: Nick escapes from the flat he's imprisoned in by dropping a piano on the villains returning there after finding he's lied to buy himself time.
Plot-Based Photograph Obfuscation: The Blurred Man, where the two criminals of the book have been running a charity using the fake persona of "Lenny Smile". When somebody asks for a photo of Lenny Smile, one of the criminals dresses up as him in a deliberately out-of-focus photograph.
Punny Name: In the first book alone there are two Germans called Gott and Himmel, a Femme Fatale called Lauren Bacardi, and a charlady called Betty Charlady.
Running Joke: Tim's inability to remember a client's name properly; 'Mr Naples' becomes 'Mr Venice', 'Mr Navels' and 'Mr Nipples' within the course of the first chapter, 'Johnny Powers' becomes 'Johnny Flowers', 'Mr Hammill' becomes 'Mr Camel', 'Mr Hubble', 'Mr Rubble' and 'Mr Rabble', etc. etc.
Twist Ending: Once in each of the first three novels; In The Falcon's Malteser, when Nick finds that Lauren has gotten to the diamonds before him, in Public Enemy Number Two when Nick realises his French teacher is the Big Bad, and in South by South East when Nick realises that Tim's girlfriend is the Big Bad.